It is well known that structures can fail when subjected to external forces of sufficient magnitude, as for example high winds or a moderate to strong earthquake. Many proposals have been made for improving the ability of a structure to withstand such forces without damage or failure of the structure. The approaches range from making the structure rigid, making it flexible, to mounting the structure upon the surface of the ground so that it can move relative to the ground, by coupling or uncoupling the structure to a mass to change its resonant frequencies, etc. One such example is shown in U.S. Pat. No. 5,036,633 invented by Kobori wherein an apparatus is disclosed for controlling the response of a structure to external forces such as seismic vibration and/or wind impacting against the structure, the control apparatus including variable stiffness means secured to and bracing the structure, variable damping means interposed between the structure and the variable stiffness means, and a computer which is programmed to monitor external forces impacting against the structure and to control the variable damping means by selecting a coefficient of damping suitable to render the structure non-resonant relative to the monitored external forces. The foregoing patent of Kobori, as well as other patents of Kobori, and patents of others, are based on feedback control principles which include changing stiffness to avoid resonance according to ground motion forecasting, changing damping coefficient according to preset damping standards, and varying the stiffness of a local member by locking or unlocking a device disposed between the ends of a member. The approach of the prior art emphasizes identifying individual structural vibration-reduction-devices, but does not perform an analysis of the whole structural system's behavior. Furthermore, the prior art analysis tends to focus on a single plane of the structure and the analysis is not three dimensional.